The invention broadly relates to electromechanical transducers which employ beam contacts to close an electrical circuit in response to a mechanical input. More specifically, the invention relates to acceleration sensors employing an inertial "sensing" mass which moves in response to acceleration from a first position within a passage to a second position therein, whereupon the sensing mass physically bridges a pair of beam contacts cantilevered into the passage.
Known cantilevered-beam contacts for use in acceleration sensors are typically stamped from a flat strip of metal and are nominally rectangular in cross-section. One end of each beam contact is securely mounted to an insulated portion of the accelerometer housing and otherwise electrically connected with an electrical lead extending from the housing. The other end or "free end" of each beam contact projects into the passage in order that it might make contact with an electrically-conductive surface on the sensing mass when the latter moves to the second position within the passage, whereby a circuit is closed to indicate such sensing mass movement.
Such known beam contacts are generally limited as to the amount of elastic travel that can be achieved at their free ends for a given package size, since each contact experiences elastic strain only along that portion of its length which actually projects into/across the passage. Moreover, such known beam contacts exhibit a tendency to take on a permanent set, i.e., experience plastic strain, when deflected by the sensing mass in the event of a substantial acceleration input to the accelerometer housing. Another common problem inherent to such known beam contacts is failure through the mechanism of fatigue, particularly where the sensor is used as a "safing" sensor, with its relatively lower threshold and correlatively frequent contact closure.